<template>
    <div class="todo-footer">
        <label>
            <input type="checkbox" v-model="isCheckAll" />
        </label>
        <span><span>已完成{{count}}</span> / 全部 {{todos.length}}</span>
        <button class="btn btn-danger" @click="clearAll">清除已完成任务</button>
    </div>
</template> 
<script lang="ts">
import { defineComponent, ref ,computed} from 'vue'
import { Todo } from '../types/todo'
export default defineComponent ({
    name: 'footer',
    props: {
        todos: {
            type: Array as () => Todo [],
            required: true
        },
        checkAll:  {
            type: Function,
            required: true
        },
        clearAll: {
            type: Function,
            required: true
        }
    },
    components: {
    },
    setup(props) {
        
        const count = computed(()=>{
            return props.todos.reduce((pre, todo , index) =>{
                return pre + (todo.isCompleted?1:0)
            },0)
        })
        const isCheckAll = computed({
            get() {
                return count.value > 0 && props.todos.length === count.value
            },
            set(val) { 
                props.checkAll(val)
            }
        })
        
        return {
            count,
            isCheckAll
        }
    }
})

</script>


<style scoped>
/* footer */

.todo-footer {
	height: 40px;
	line-height: 40px;
	padding-left: 6px;
	margin-top: 5px;
}

.todo-footer label {
	display: inline-block;
	margin-right: 20px;
	cursor: pointer;
}

.todo-footer label input {
	position: relative;
	top: -1;
    vertical-align: middle;
    margin-right: 5px;
}

.todo-footer button {

    float:right;
    margin-top: 5px;
}
</style>